I have to agree with
Old Navy...be very careful going behind the neck. They have real value but if you do them make sure to:
- Do not go below earlobe height.
- Use lower weight & higher reps (i.e. don't go 6-8 reps go 15-20)
- Pre-stretch those shoulders, warm them up and do rotator cuff work before this exercise
- Stop if they pop
You might want to use the Smythe Machine and do them seated, controled and let the weight brush the back of the head (don't go any further behind). Again lower weight & higher reps for behind the necks.
If you must go behind the neck consider doing it later in the shoulder rotation and/or use pre-exhaust methods first...this will reduce the weight you need. If you do this use the Smythe machine...that way you won't use those tired stabilizers and hopefully decrease injury.
If you must go behind the neck consider using them only occassionaly and choose other presses as the main exercises.
As for Hammer Strength it is OK but by itself it won't build massive shoulders. Instead rely on the BB Military Press both standing and seated; DB presses standing, seated (using both parallel and palms forward grips), Arnolds; Push Presses (BB and Smythe); Smythe Machine Presses to the front; Clean and Presses.
Heavy Rows & Deads will hit the rear delts.
Side delts are built with presses not laterals...but if you need them Glass laterals (pinkie high throught the movement) work well.
Most guys discover as they get older that the low rep work (i.e. 6-8) they did in their younger days wasn't as productive as higher rep work. Also rotator cuff injuries from heavy sets and/or behind the neck work occuring in their younger days never completely heal and so they must always be extra careful cus the tenderness is always lurking. Something to consider.